Telephone system with high-frequency oscillations



Sept. 22. 1925. 1,554,345

E. HABANN TELEPHONE SYSTEI WITH HIGH FREQUENCY OSCILLATIONS Filed Auz. 22, 1921 3 Shedts-Shoot 1 3 5 lnferrupfer' 1 IDHIONE% g 2 4/ kmgl ygr' WW 7 7 91 2 r r 10.

Unvenfor Sept. 22, 1925. 1,554,345

u E. HAB ANN TELEPHONE SYSTEM WITH HIGH FREQUENCY OSC-ILLATIONS Filed Auz; 22, 1921 s Shets Sho ep z anvenfo'ra- @Mizz Sept. 22, 1925.

E. HABANN TELEPHONE SYSTEM WITH HIGH FREQUENCY oscILLA'rI ous Filed Auzi 22, 1921 Santa-Shoot 3 v 1A? fig 4-.

tria th August, 1921, in Hungary Patented Sept. 22,1925. i

UNITED STATES PATENT OFFICE.

ERICK HABANN, OF' WAIDMLNNSLUST, NEAR BERLIN, GERMANY.

TELEPHONE SYSTEM WITH HIGH-FREQUENCY OSGILLA'IIONS.

Application filed August 22, 1921. Serial No. 494,400.

in Italy 28th March, 1921, in Sweden 31st March, 1920, and March 17th, 1921, in Au? 26t 1 August, 1921, 1n Belgium 30th March, 1921, and in France 25th March,-1921, of whlch the following is a specification.

The invention relates to a system of tele phony by means of high frequency oscillations wherein the transmission is effected either as wireless or-and this is preferable by double wire line. L

The methods hitherto known for telephony by means of high frequency oscillations are based on the principle that a particular high frequency generator produces damped or undamped oscillations which are transmitted in the lin the amplitudes thereof being varied by the superimposed speaking currents.

The object of the invention is another method, wherein the low frequency speaking currents serve themselves for producing the high frequency oscillations. For thls purpose the microphone currents, preferably after amplification, are divided into impulses by an interrupter, operating at a higher frequency than audible frequency, and are supplied in this interrupted form to an oscillatin circuit which is thus excited and thus osclllates with its own frequency.

Each circuit closure at the interrupter therefore sets up a high frequency wave train which is delivered by the oscillating circuit. The initial maximum amplitude value of this wave train correspond to the speaking current which is energy supplied to the interrupter at the moment of interruption. By this characteristic curve therefore speech oscillations are produced in the distant telephoneby means of a rectifying or an inteating device such as a so called detector with the known circuits.

The number of impulses into which the 9 speech curve is dissolved ismade either equal to the number of oscillations of the oscillating circuit or less than these, but not greater, as otherwise .it would beimpos'sible or the oscillation of the circuit itself to take place in the period between two impulses. Onthe other-hand care shouldalso be taken that the oscillations in the oscillating circuit do not cease between two impulses as'otherwise a loss of energy would be caused. Care must therefore be taken to have a sufficiently small damping of the oscillating circuit and according to the invention this may be effected by providing a second oscillating circuit of small damping which is coupled between the first oscillating circuit and, the line. i

'As the high frequency oscillation, which acts as carrier for the speech, does not have a constant amplitude, oscillations of a higher range, which would otherwise be associated therewith and would disturb the speech, are avoided. An important advantage of the invention however consists in that the oscih.

lation's only enter the distant line when speaking into the telephone. It is therefore unnecessary to render the interrupter or the oscillating circuit inoperative or disconnect it from the line in order to prevent interference from neighbouring lines, but the device is always kept ready for operation.

The interrupter may either be a mechanical or electromagnetic interrupter (contact wheel) or even a liquid'interrupter, further, however, it may, according to the invention, be also formed as a discharge tube as will be described hereinafter with reference to Figures 3-6. According. to the invention this tube is combined with an oscillating circuit in such a manner that it forms in itself a high frequency generator whichsupplies the necessary continuous current 0r low frequency alternating current for its operation.

Figures 1 and 2 of the drawings show firstly the basic principle of the invention for single wherein asuitable interrupter of the first and multiplex transmission mentioned type is used. In Figs. 3 to 6 an which are tuned to different wave lengths and in their turn are coupled to the distant cable 17 or an antenna.

The impulses supplied by the interrupter may, when the interrupter runs and should run comparatively slowly, first be conducted to a frequency transformer which increases the number of impulses in the known manner.

Figure 3 shows an arrangement according to the invention wherein a cathode tube R is employed as an interrupter. In this case an ionization space is provided between the anode a and the glowing cathode is of the tube R, this ionization space being supplied by a suitable high frequency wave generator HR The ionization interval is arranged in air or in a gas and any type of known discharge tube may be used. Instead of the glowing cathode a cathode of alkali metal and a rare gas filling may be used. In the ion stream'which passes from the cathode is to the anode a, are disposed two middle electrodes G G For the sake of clearness these are shown in the drawing as one above another. These middle electrodes are who referably formed as grids or spirals lie in the same plane, without contacting with one another. In this manner a disturbing potential difference between these electrode in the ion stream is avoided. To

' tential difference between the grids G G when no speaking current is imparted thereto. The battery D supplies the heating current for the, glowing cathode is.

. In'the circuit of the grids G G is arranged an oscillating circuit OJ and a condenser C,, which couples up the speaking apparatus TM.

The apparatus TM consists of the usual auxiliary apparatus with microphone m, microphone battery e, telephone 25 and transmitter u. in the known manner. The oscillating circuit OJ is directly coupled to the distant line L so as to avoid the use of a separate transformer.

The operation is as follows: As soon as the high frequency source HF has been put into circuit, ions pass from is to a in the valve. These thus connect the grids G G together electrically, but this at first does not produce a current in the circuit 0,, C, J, D. Currents only occur in this circuit when speakin .into the microphone of the apparatus Tl\ which however in rhythm with the high frequency are closed at G G The oscillating circuit CJ is thus actuated in the same rhythm and transmits the high frequency waves into the line L. These waves have a rising and falling amplitude of which the curve illustrates the speaking oscillation.

In the distant receiver this curve is rendered audible as speech by known means.

The arrangement of the electrodes forming the interrupting space at the same potential may also be such that two entwined spirals are used as electrodes, or one electrodewith any one shapemay surround the other completely or partially. The plane or longitudinal axis of these electrodes need not be at right angles to the connecting line of the other electrodes (70, a) producing the ionization, whilst, for example, two plate shaped electrodes may be so arranged opposite one anothenthat they form between them an interrupting space lying transversely to the stream of ions. Two grids of the type hereinbefore described may have their plane disposed in the ion stream.

Instead of heating only one of the electrodes, which form the ionization space, as described, both these electrodes may be heated. Both may also be of the same material, for example, alkali metal. The electrodes forming the interrupting space may be of any suitable material.

In Figure 4 the tube R is filled with rare as and 1s provided with an anode A, which 1s connected to the positive pole of abattery B over a resistanceor damping coiljW, an alkali metal cathode K connected to the negative pole of the same battery B, and finally wlth two middle electrodes G G which are in the form of plates, for example, and have their surface in the direction of the ion stream passing from K: to A. Between K and A is a branch provided with a self inductance L and a capacity G which helps to form the known Poulsen sponding primary coil is in the circuit of a microphone m and the corresponding battery e L which passes from K through Gr L BC,

Gr to A or vice versa according to the po tcntial at the time at Gr G This current is transmitted to the antenna which thus continuously radiates waves only during actual speaking but not during the word pauses. B th1s restriction to the eriod of speaking t e oscillations of the circuit L C, are prevented from influencing the distant or neighbouring receivers.

The ener y radiated by the antenna is practically t e energy of the battery B converted into high frequency by the oscillatin circuit L 0,.

igure 5 shows a circuit arrangement wherein the tube is provided with a glowing filament cathode K which is su plied b a battery 0. The middle electro es 6", G are formed for example as entwined spirals. This is for the purpose of increasing the necessary traversing potential at each oscillation, whereby a higher charging of the condenser C is obtained and the oscillating energyof the circuit LC, and thus also the energy produced by the tube is increased. In this case the high frequency is transmitted to a distant line F by a coupling by means of an oscillating circuit L G which at the same time transforms the high frequency into the required wave' for the line. Such a second oscillating circuit allows of quite a general regulation of the frequency, without it being necessary to vary the oscillating circuit L C, of the tube.

In Figure.6 the tube is provided with a potassium cathode K, an anode A, two grids G G and two additional electrodes G G which are formed as entwined grids or grates (finger grids). The tube is supplied by a battery B and is reactively coupled to the oscillating. circuit L, C, in the known manner by the grid G Also in this case the high frequency current produced in the tube does not influence the gridcs G G which are at the same potential, as long as they remain at the samepotential, whilst a. strong. actuation occurs as soon as the microphone mis spoken into as the grids thusbecome different relative potential. In this case the microphone with its battery 0, is in parallel with an induction coil J and a block condenser BC, whereby a battery e compensates the battery e, in the circuit of the electrodes G G The high fre uency current taken from the tube is int is case also transmitted to an oscillating circuit L G, as in Figure 5 which is coupled to the distant cable F and transmits into the latter a high'frequencyalternating current which is the carrier for the speaking sounds. A special type of tube is notrequired for the purpose of the invention. The tube can be lled with a gas such for example, as a rare gas, or metal vapour, (for example a rare gas) or with metal vapor (for example mercury vapour). The known electrode arrangements are applicable with their proper advantages. For example insteadof using a constantly heated cathode, a continuously glowing cathode in rare gas may be used.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is.

1. A high frequency transmitting station for telephony, consisting of an oscillating circuit without current generator being switched therein, a local microphone circuit coupled with the said oscillating circuit, a communication line coupled with the said oscillating circuit, a current interrupter device actuating with a number ofinterruptions above audible range and adapted to interrupt the alternating microphone currents transmitted into the oscillating circuit and means for avoiding the continuous local microphone-current from being transmitted into the interrupter and oscillating circuit, substantially as described.

2. A high frequency transmitting station for telephony, consisting of an oscillating 'circuit without current generator being switched therein, a local microphone circuit coupled with the said oscillating circuit a communication line coupled with the said oscillating circuit, amechanical rotar current-interrupter actuating with a num er of interruptions above audible range and adapted to interrupt the alternating microphone currents transmitted into the oscillating circuit and means for avoiding the continuous local microphone current'from being transmitted into the interrupter and oscillating circuit, substantially as described.

3. A high frequency transmitting station for telephony, consisting of an oscillating circuit without current generator being switched therein, a local microphone circuit coupled with the said oscillating circuit, a communication line coupled with the said oscillating circuit, an ionization tube actuating as currentinterrupter with a number of interruptions above audible range, and adapted to interrupt the alternating microhone currents transmitted into the oscil- D ating circuit and means for avoiding the continuous local microphone current from bein transmitted into the interrupter and oscillating circuit, substantially as described.

4. A high frequency transmitting station for telephony, consisting of an oscillating circuit without current generator being switched therein, a local microphone circuit coupled with. the said oscillating circuit, a communication line coupled with the said oscillating circuit, an ionization tube arranged in series with the said oscillating circuit and adapted to interrupt the alternating microphone currents transmitted into the oscillating circuit with a number of interruptions above audible range and means for avoiding the continuous local microphone current from being transmitted into the interrupter and oscillating circuit, substantially as described.

5. A high'frequency transmitting station for telephony, consisting of an oscillating circuit without current generator being switched therein, a local microphone circuit coupled with the said oscillating circuit, a communication line coupled with the said oscillating circuit, an ionization tube with two middle electrodes, the two end-electrodes being connected through an alternating/ current source, the said middle electrodes being arranged in series with the said oscillating circuit and adapted to interrupt the alternating microphone currentstransmitted into the oscillating circuit with a number of interruptions above audible range and means for avoiding the continuous localmicrophone current from being transmitted into the interrupter and oscillating circuit, substantially as described.

6. A' high frequency transmitting station for multiplex telephony, consisting of a plurality of oscillating circuits, none of which possesses a current generator, aplurality of local microphone circuits, each one coupled with one of the said oscillating cirj cuits, a communication line coupled with all of the oscillating circuits, a current interrupter commonly arranged to interrupt all the alternating microphone currents transmitted into the oscillating circuits with a number of interruptions above audible range and means for avoiding the cintinuous local microphone current from being transmitted into the interrupter and oscillating circuit, substantially as described.

In testimony whereof I have affixed my signature.

ERICH I-HXBANN. 

